The present invention relates to a contact apparatus suitable for a relay of a power load or an electromagnetic switch.
In a contact apparatus used for opening and closing a power supply of an electrically running automobile, relatively great DC current as great as 100A is switched. In such a contact apparatus, it is difficult to swiftly break the current due to arc generated between contacts when an electric path is opened. Thereupon, Japanese Patent Application Laid-Open No. H8-45411 for example discloses a contact apparatus having an insulator which is heated by heat of an arc for generating arc-extinguishing gas, in which the arc is cooled by the arc-extinguishing gas, thereby enhancing the breaking performance.
However, if the insulator for generating the arc-extinguishing gas is merely provided, a voltage rising speed of the arc generated between contacts is small, and there is a problem that excellent breaking performance can not always be obtained.
The present invention has been accomplished in view of the above problem, and it is an object of the invention to provide a contact apparatus in which a voltage rise of an arc generated between contacts is abruptly generated to enhance the breaking performance of an electric path.
A contact apparatus of the present invention comprises a fixed contact having a fixed contact point, a movable contact provided with a movable contact point which is connected to and separated from the fixed contact point, and a driving mechanism for driving the movable contact, wherein a permanent magnet is disposed in a vicinity of a region where the fixed contact point and the movable contact point are located, an arc generated when the fixed contact point and the movable contact point are separated from each other is formed so that arc is moved sideways from the opposed region between the fixed contact point and the movable contact point by magnetic force of the permanent magnet and the arc is stretched.
In the contact apparatus of such a structure, the arc generated between the fixing contact point and the movable contact point when the electric path is opened is moved sideways by the magnetic force of the permanent magnet and stretched. The arc length is increased and thus, the arc voltage rises. With this, the arc is swiftly extinguished, and the breaking performance of the electric path is enhanced.
In addition to the above, if an arc-extinguishing member made of insulative material capable of generating arc-extinguishing gas is provided in a region near the fixed contact point and the movable contact point, the arc is cooled by the arc-extinguishing gas. With this, the arc voltage further rises, the breaking performance of the electric path is further enhanced.